The present invention relates to a rear axle for a motor vehicle, especially for a four-wheel drive motor vehicle with a torsionally soft cross bearer.
A wheel suspension with a torsionally soft cross bearer and with welded-on longitudinal guide members for a motor vehicle is disclosed in the German Pat. No. 21 03 399. The wheels are supported at these longitudinal guide members, whereby only the wheels of the further axle are driven. With the use of such a rear axle for a four-wheel drive motor vehicle, in which the drive shaft is extended up to a differential arranged to the rear of the cross bearer of this axle, the drive shaft would considerably reduce the ground clearance of the vehicle.
It is the object of the present invention to provide a rear axle of the aforementioned type which enables an arrangement of the drive shaft with equal road clearance as is made possible at the further axle and can be used both with a four-wheel drive as also with a single-axle drive.
The underlying problems are solved according to the present invention in that the cross bearer includes a center portion with an opening for a drive shaft, and this opening has such a size that the drive shaft lies approximately inside of the interior contour formed by the cross section of the bearer.
The principal advantages obtained with the present invention reside in that the same rear axle can be used with single-axle and four-wheel drives so that with a refitting, for example, from single-axle drive to four-wheel drive, the rear axle does not have to be exchanged and thus a cost-favorable solution is created. However, also an exchange of the rear axle is without problems because the suspension points are identical for the two constructions, and no additional adjustments have to be undertaken.
The drive shaft extends through the cross bearer of the axle in such a manner that an approximately constant road clearance is assured over the entire vehicle length. In order that no relative movements of the cross bearer take place during the inward and outward spring movement and impair the drive shaft, the cross bearer at the same time forms the axis of rotation of the guide members.
The drive shaft is preferably arranged inside of the interior contour formed by the cross section of the cross bearer so that it extends from the front axle without bending to the rear differential.
The simplification of the rear axle is also assisted in that in the transition from the cross bearer to the longitudinal guide members, no complicated connection or gusset plates with corresponding welded places are necessary. The cross bearer consisting of hot-pressed part is provided with a knee-shaped, formed-on portion at the ends thereof for the connection with the longitudinal guide members which partially form-lockingly surrounds the longitudinal guide member. The welding seams of the connection are provided within the area of smallest possible stresses, whereby also no significant shearing stress occurs within this area.